1. Field of the Invention
The present invention relates to an optical scanning device.
2. Description of the Related Art
Conventionally, an optical scanning device is known that includes a movable plate that has an optical reflection surface for reflecting incident light, a torsion beam that supports the movable plate in such a way that the movable plate is enabled to rotate around the torsion beam, and a drive source that applies a force in a twisting direction to the torsion beam.
In case of using the above-described optical scanning device for an image display device, if scanning speed is not constant, an image will be distorted in a scanning direction. Therefore, only an area in which the scanning speed is constant is used for displaying an image. In order to make the scanning speed constant, it is required that a voltage with high linearity, i.e., a voltage whose waveform has a long straight line section in one period can be applied to the drive source.
Therefore, conventionally, a section, in which the scanning speed of the optical scanning device is constant, is caused to be longer by applying a voltage that has a sawtooth waveform to the drive source (e.g., refer to Patent Document 1). With respect to the above, when a voltage that has a sawtooth waveform is applied to the drive source, due to frequency components corresponding to the mechanical natural frequency related to driving a mirror, and due to harmonic components of the natural frequency, what is known as a ringing phenomenon occurs when driving the mirror. Therefore, the frequency components corresponding to the natural frequency and the harmonic components of the natural frequency are removed by using a filter such as a notch filter.